Re: intel 64-bit processors with amd instruction sets: (was [nvda] A word of warning about xp and windoows update enabled systems with old amd processors


Mike Sedmak
 

AMD processors have had SSE2 support for more than 10 years.

Unfortunately the x86 instruction set does not stand still. And if
developers want to get the performance advantages offered by the new
instructions they have two choices:
1. Add complexity to their code and check feature bits to see which
extensions are supported on your machine. Then have separate code
for the supported legacy combinations.
2. Drop support for older CPUs from both AMD and Intel to reduce the
number of copies of the code routines they have to maintain.

Also note, that some of the code which is not backwards compatible
might come from libraries that the end developer does not own
themselves.

Mike

On 12/16/16, Brian's Mail list account <bglists@blueyonder.co.uk> wrote:
Yes I notice this. The other issues that I was on about with ref to older
amd processors are those early Athlon/Sempron ones that had 3D Now! code
instead of SSE 2. Some software supported this, but most did not, falling
back to inefficient older ways as has apparently happened in some recent
windows updates, which has caused the single core old amds to effectively
run at full whack and have no time to actually do any computing!
Turn of automatic updates and the routines Microsoft now seem to use get
switched off until you are sure there are updates to be downloaded, then go

off and have a holiday while they install.
Pritty soon those machinenes mostly running xp and Vista, will be unusable

in any case, but I still think there will be a smattering of oddball dead
end chips around that will only show their true colours on some software.
Maybe there should be ahome for retired old processors!

Brian

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----- Original Message -----
From: "Joseph Lee" <joseph.lee22590@gmail.com>
To: <nvda@nvda.groups.io>
Sent: Thursday, December 15, 2016 5:03 PM
Subject: Re: intel 64-bit processors with amd instruction sets: (was [nvda]

A word of warning about xp and windoows update enabled systems with old amd

processors


Hi,
The following is a bit technical, so please bear with me for a second:
Almost two decades ago, many microprocessor manufacturers noted that the
32-bit 4 GB limit would be reached within a few years, hence development
of
64-bit processors began. Intel and AMD took two different routes: Intel
came
up with a completely different 64-bit architecture than that of Pentium,
while AMD extended Pentium's language and made it work with 64-bit data.
Eventually, Intel adopted AMD's approach, hence you'll find that even for
Intel processors, the architecture name is AMD64 (technically called
x86-64). Modern 64-bit processors from Intel and AMD can run 32-bit
software
such as NVDA because they can understand 32-bit instructions natively in
hardware, and Windows and other operating systems have mechanisms to
allow
32-bit software to run under 64-bit operating systems (I'll describe this
process from start to finish upon request).
Cheers,
Joseph
P.S. To Derek and other devs: at some point, we should explain what WoW64
is.

-----Original Message-----
From: nvda@nvda.groups.io [mailto:nvda@nvda.groups.io] On Behalf Of
Travis
Siegel
Sent: Thursday, December 15, 2016 8:46 AM
To: nvda@nvda.groups.io
Subject: intel 64-bit processors with amd instruction sets: (was [nvda] A
word of warning about xp and windoows update enabled systems with old amd
processors

Perhaps companies don't support it, but they should. I have an intel
processor, but it uses the amd command set. In fact, if I do a system
info,
it tells me intel processor, (with all it's various version information),
then tells me amd-64, then returns to intel for processor type and so on.
It's very odd, but I have discovered that intel 64-bit programs don't
work
on this machine, only amd-64 apps work (go figure)

This is an all in one computer, so it's likely using one of the intel
laptop
processors that have the power saving features of a laptop, but
apparently,
these cpus are also using amd commands for their command sets. <shrug>



On 12/15/2016 6:10 AM, Brian's Mail list account wrote:
I noticed yesterday on an old XP Athlon machine, the chip with no sse
2, that after a latest xp security update which is enabled on that
machine, the processor usage was 99 percent. trying this on a second
machine running a sempron resulted in the same issue, but not on the
old Pentium Intel chipped machines.
The thing is it seems to have altered the way the software looks for
and downloads windows updates, so to stop this problem you need to
turn off automatic updates. This can be quite a challenge with about 1
percent processor still working when nvda tends to need 143 percent,
but after doing this and rebooting all is sweetness and light again. I
only put this on here as I know a lot of folk in some of the poorer
countries out there still use xp machines with the get updates hack on
them, and wanted to help.
I'll shut up about it now, as in fact its off topic.
I imagine Microsoft never bother to test it on this processor as so
many companies now do not support it, like dropbox or firefox to name
but two.


Brian

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